Electrolyte membrane, preparation method and lithium ion battery

Abstract

The invention discloses an electrolyte membrane and a preparation method thereof and a lithium ion battery, and the preparation method of the electrolyte membrane comprises the following steps: after arranging a composite electrolyte material on one side or two sides of a porous polyimide fiber membrane, sequentially carrying out hot pressing treatment and cold pressing treatment, enabling a composite electrolyte material to enter the porous polyimide fiber membrane to prepare a composite electrolyte layer; wherein the composite electrolyte material comprises a polymer electrolyte, a filler and a lithium salt in a mass ratio of (8-12): (1-6): (1-8). On the basis of the porous polyimide fiber membrane, the polymer electrolyte and the filler in the composite electrolyte material are filled into pore channels of the porous polyimide fiber membrane by utilizing the composite electrolyte material containing the polymer electrolyte and the filler and matching with pressurization treatment; a continuous ion transmission channel is formed to provide a continuous transmission channel for lithium ions, and the electrolyte membrane with good ion conductivity and mechanical strength is obtained.

Description

Technical Field

[0001] The present application relates to the field of batteries, and particularly to an electrolyte membrane and a preparation method thereof, as well as a lithium-ion battery. Background Art

[0002] Solid-state lithium-ion batteries are a new energy storage technology centered around solid electrolytes. By replacing the liquid electrolyte and separator in traditional lithium-ion batteries with solid media, the conduction of lithium ions between electrodes is achieved. Compared with traditional liquid electrolyte systems, solid electrolytes (such as sulfides, oxides, or polymer materials) have characteristics such as non-flammability and high mechanical strength, which can significantly inhibit the growth of lithium dendrites, fundamentally solve the risks of flammability, leakage, and thermal runaway in liquid electrolyte systems, and are also compatible with lithium metal anodes (theoretical capacity 3860 mAh / g) and high-voltage cathode materials, enabling the theoretical energy density to exceed 500 Wh / kg, providing technical support for the long-range driving of electric vehicles and the thin and light design of consumer electronics.

[0003] Among traditional solid electrolytes, inorganic solid electrolytes have high ionic conductivity and good thermal stability, but they have high hardness, poor interfacial contact, and high cost; organic solid electrolytes have good flexibility, good interfacial contact, and low cost, but have low room-temperature ionic conductivity. Summary of the Invention

[0004] Based on this, it is necessary to provide an electrolyte membrane, a preparation method thereof, and a lithium-ion battery that have both good ionic conductivity and mechanical strength.

[0005] An embodiment of the present application provides a method for preparing an electrolyte membrane, including the following steps:

[0006] After a composite electrolyte material is disposed on one or both sides of a porous polyimide fiber membrane, hot pressing treatment and cold pressing treatment are sequentially performed to allow the composite electrolyte material to enter the porous polyimide fiber membrane, thereby preparing a composite electrolyte layer;

[0007] Wherein, the composite electrolyte material includes a polymer electrolyte, a filler, and a lithium salt in a mass ratio of (8 - 12) : (1 - 6) : (1 - 8).

[0008] In one embodiment, the hot pressing treatment satisfies one or more of the following conditions:

[0009] (1) The temperature of the hot pressing treatment is 50°C to 140°C;

[0010] (2) The pressure of the hot pressing treatment is 2 MPa to 10 Mpa;

[0011] (3) The time of the hot pressing treatment is 4 min to 15 min.

[0012] In one embodiment, the cold pressing treatment satisfies one or more of the following conditions:

[0013] (1) The temperature of the cold pressing treatment is 20°C to 40°C;

[0014] (2) The pressure of the cold pressing treatment is 2 MPa to 10 MPa;

[0015] (3) The time of the cold pressing treatment is 4 min to 15 min.

[0016] In one embodiment, the porous polyimide fiber membrane satisfies one or more of the following conditions:

[0017] (1) The thickness is 10 μm to 15 μm;

[0018] (2) The porosity is 70% to 90%;

[0019] (3) The equivalent pore size is 0.6 μm to 11 μm.

[0020] In one embodiment, the preparation method of the composite electrolyte layer includes the following steps:

[0021] Mix the composite electrolyte materials according to the mass ratio, heat to 40°C to 60°C, and prepare a mixed material;

[0022] Coat the mixed material on one or both sides of the porous polyimide fiber membrane, and after drying, perform hot pressing treatment and cold pressing treatment in sequence.

[0023] In one embodiment, one or more of the following conditions are satisfied:

[0024] (1) After heating to 40°C to 60°C, mix for 5 h to 18 h to prepare the mixed material;

[0025] (2) The drying time is 0.5 h to 15 h;

[0026] (3) The drying temperature is 10°C to 120°C;

[0027] (4) The composite electrolyte material further includes a solvent, and the ratio of the solvent to the polymer electrolyte is (100 - 200) mL : (8 - 12) g;

[0028] (5) The single-sided thickness of the mixed material coated on the porous polyimide fiber membrane is 200 μm to 600 μm.

[0029] In one embodiment, the composite electrolyte material satisfies one or more of the following conditions:

[0030] (1) The polymer electrolyte includes one or more of polyacrylic acid, polyvinylidene fluoride, polyvinylidene fluoride - hexafluoropropylene, polyethylene oxide, and polyacrylonitrile;

[0031] (2) The filler includes one or more of lithium lanthanum zirconium tantalum oxide solid electrolyte, lithium lanthanum zirconium oxide solid electrolyte, lithium titanium aluminum phosphate solid electrolyte, lithium germanium aluminum phosphate solid electrolyte, and lithium lanthanum titanate solid electrolyte;

[0032] (3) The lithium salt includes one or more of CH2LiNOS, LiN(CN)2, Li(CF3SO2)3C, LiC4F9SO3, LiN(SO2CF2CF3)2, LiB(C2O4)2, LiBOB, LiBF4, LiBF3(C2F5), LiODFB, LiTFSI, LiFSI, LiAsF6, LiSbF6, and LiClO4.

[0033] This application also provides an electrolyte membrane prepared by the above - mentioned preparation method.

[0034] In one embodiment, one or both of the following conditions are satisfied:

[0035] (1) The thickness of the electrolyte membrane is 15 μm - 25 μm;

[0036] (2) The total thickness of the composite electrolyte layer is 5 μm - 10 μm.

[0037] This application also provides a lithium - ion battery, including a positive electrode, a negative electrode, and an electrolyte disposed between the negative electrode and the positive electrode, and the electrolyte includes the electrolyte membrane as described above.

[0038] Based on a porous polyimide fiber membrane, this application uses a composite electrolyte material containing a polymer electrolyte and a filler, and with the cooperation of pressure treatment, the polymer electrolyte and the filler in the composite electrolyte material are filled into the pores of the porous polyimide fiber membrane to form a continuous ion - transport channel to provide a continuous transport channel for lithium ions, and obtain an electrolyte membrane with both good ionic conductivity and mechanical strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0040] Figure 1SEM image of the porous polyimide fiber membrane used in Example 1;

[0041] Figure 2 SEM image of the electrolyte membrane prepared in Example 1;

[0042] Figure 3 Electrochemical impedance spectrum of the electrolyte membrane prepared in Example 1. The abscissa is the real part of the impedance Z', and the ordinate is the negative imaginary part of the impedance -Z'';

[0043] Figure 4 Tensile resistance of the electrolyte membranes prepared in Example 1 and Comparative Example 1. The abscissa is the strain, and the ordinate is the tensile strength;

[0044] Figure 5 Linear sweep voltammogram of the electrolyte membrane prepared in Example 1. The abscissa is the voltage, and the ordinate is the current;

[0045] Figure 6 Charge-discharge cycle data of the LiFePO4 / / Li solid-state battery with the electrolyte membranes prepared in Example 1 and Comparative Example 1 at a rate of 0.5C. The abscissa is the number of cycles, the left ordinate is the capacity, and the right ordinate is the Coulomb efficiency. Detailed implementation manners

[0046] This application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the disclosure of this application more thorough and comprehensive. Of course, they are only examples and are not intended to limit this application. In addition, this application may repeat reference numerals and / or letters in different examples. This repetition is for the purpose of simplicity and clarity and does not itself indicate the relationship between the various embodiments and / or arrangements discussed.

[0047] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of these features. In the description of this application, the meaning of "a plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined. In the description of this application, the meaning of "several" is at least one, such as one, two, etc., unless otherwise clearly and specifically defined.

[0048] Unless otherwise specified, all percentages, fractions, and ratios are calculated based on the total mass of the compositions of this application. Unless otherwise specified, all masses of the listed components are given as the content of the active substance, so they do not include solvents or by-products that may be contained in commercially available materials. The term "mass percentage content" in this article can be represented by the symbol "%".

[0049] The terms used herein are for the purpose of describing particular embodiments only and are not intended as a limitation of the present application. As used herein, the singular forms "a", "an" and "the" are also intended to include the plural forms unless the context clearly dictates otherwise. It should also be understood that the terms "comprising" and / or "including", when used in this specification, specify the presence of the stated features, integers, steps, operations, elements and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups. As used herein, the term "and / or" includes any and all combinations of the associated listed items.

[0050] Unless stated to the contrary, the singular forms of terms may include the plural forms and should not be construed as being in the singular number.

[0051] As used herein, "comprising", "including", "containing", "having" or other variants are intended to cover non-closed inclusion, and no distinction is made between these terms. The term "including" means that other steps and components may be added without affecting the final result. The term "including" also includes the terms "consisting of" and "consisting essentially of". The compositions and methods / processes of the present application comprise, consist of and consist essentially of the essential elements and limitations described herein and any additional or optional ingredients, components, steps or limitations described herein. No distinction is made between the terms "efficacy", "performance", "effect" and "function" herein.

[0052] The terms "preferably", "more preferably", etc. in the present application refer to embodiments of the present application that may provide certain beneficial effects in certain cases. However, in the same or other cases, other embodiments may also be preferred. In addition, the recitation of one or more preferred embodiments does not imply that other embodiments are not available, nor is it intended to exclude other embodiments from the scope of the present application.

[0053] When a numerical range is disclosed herein, the above range is considered continuous and includes the minimum and maximum values of the range, as well as every value therebetween. Further, when the range refers to integers, every integer between the minimum and maximum values of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all sub-ranges subsumed therein.

[0054] An embodiment of the present application provides a method for preparing an electrolyte membrane, comprising the following steps:

[0055] After a composite electrolyte material is provided on one or both sides of a porous polyimide fiber membrane, hot pressing treatment and cold pressing treatment are sequentially carried out to allow the composite electrolyte material to enter the porous polyimide fiber membrane, thereby preparing a composite electrolyte layer.

[0056] Among them, the composite electrolyte material includes a polymer electrolyte, a filler, and a lithium salt with a mass ratio of (8 - 12) : (1 - 6) : (1 - 8).

[0057] This application is based on a porous polyimide fiber membrane. By using a composite electrolyte material containing a polymer electrolyte and a filler, and cooperating with a pressing treatment, the polymer electrolyte and the filler in the composite electrolyte material are filled into the pores of the porous polyimide fiber membrane to form a continuous ion transport channel to provide a continuous transport channel for lithium ions, thereby obtaining an electrolyte membrane with both good ionic conductivity and mechanical strength.

[0058] Furthermore, the pressing treatment can enable the composite electrolyte material to be in full contact with the fiber structure in the porous polyimide fiber membrane, and can also effectively control the overall thickness and uniformity of the membrane sheet.

[0059] In a specific example, the temperature of the hot pressing treatment is 50°C to 140°C. Specifically, the temperature of the hot pressing treatment can be but is not limited to 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, or 140°C.

[0060] Furthermore, the temperature of the cold pressing treatment is 20°C to 40°C. Specifically, the temperature of the cold pressing treatment can be but is not limited to 20°C, 25°C, 30°C, 35°C, or 40°C.

[0061] In a specific example, the pressures of the hot pressing treatment and the cold pressing treatment are each independently 2 MPa to 10 Mpa. It can be understood that the pressures of the hot pressing treatment and the cold pressing treatment can each independently be but are not limited to 2 MPa, 3 MPa, 4 MPa, 5 MPa, 6 MPa, 7 MPa, 8 MPa, 9 MPa, or 10 MPa.

[0062] In a specific example, the times of the hot pressing treatment and the cold pressing treatment are each independently 4 min to 15 min. The times of the hot pressing treatment and the cold pressing treatment can each independently be but are not limited to 4 min, 5 min, 6 min, 7 min, 8 min, 9 min, 10 min, 11 min, 12 min, 13 min, 14 min, or 15 min.

[0063] In a specific example, the thickness of the porous polyimide fiber membrane is 10 μm to 15 μm; the porosity of the porous polyimide fiber membrane is 70% to 90%; the equivalent pore size of the porous polyimide fiber membrane is 0.6 μm to 11 μm.

[0064] Specifically, the thickness of the porous polyimide fiber membrane can be, but is not limited to, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm or 15 μm. The porosity of the porous polyimide fiber membrane can be, but is not limited to, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89% or 90%. The equivalent pore size of the porous polyimide fiber membrane can be, but is not limited to, 0.6 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm, 7.5 μm, 8 μm, 8.5 μm, 9 μm, 9.5 μm, 10 μm, 10.5 μm or 11 μm. It can be understood that the above equivalent pore size is measured by the gas adsorption and desorption method and obtained by BET measurement.

[0065] In a specific example, the polymer electrolyte includes one or more of polyacrylic acid PAA (molecular weight Mw less than or equal to 600000), polyvinylidene fluoride PVDF (molecular weight Mw less than or equal to 600000), polyvinylidene fluoride - hexafluoropropylene PVDF - HFP (molecular weight Mw less than or equal to 800000), polyethylene oxide PEO (molecular weight Mw less than or equal to 1000000), and polyacrylonitrile PAN (molecular weight Mw less than or equal to 400000).

[0066] In a specific example, the filler includes lithium lanthanum zirconium tantalum oxide Li 6.75 La3Zr 1.75 Ta 0.25 O 12 solid electrolyte, lithium lanthanum zirconium oxide Li7La3Zr2O 12 solid electrolyte, lithium aluminum titanium phosphate Li 1.5 Al 0.5 Ti 1.5 (PO4)3 solid electrolyte, lithium aluminum germanium phosphate Li 1.5 Al 0.5 Ge 1.5 (PO4)3 solid electrolyte, and lanthanum lithium titanate La 0.5 Li 0.5One or more of the TiO3 solid electrolytes. Further, the particle size of the filler is 0.3 μm to 4 μm. Specifically, the particle size of the filler can be, but is not limited to, 0.3 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, or 4 μm.

[0067] In a specific example, the lithium salt includes one or more of CH2LiNOS, LiN(CN)2, Li(CF3SO2)3C, LiC4F9SO3, LiN(SO2CF2CF3)2, LiB(C2O4)2, LiBOB, LiBF4, LiBF3(C2F5), LiODFB, LiTFSI, LiFSI, LiAsF6, LiSbF6, and LiClO4.

[0068] In a specific example, the method for preparing the composite electrolyte layer includes the following steps:

[0069] Mix the composite electrolyte materials according to the mass ratio, heat to 40 °C to 60 °C, and prepare a mixed material.

[0070] Coat the mixed material on one or both sides of the porous polyimide fiber membrane. After drying, perform hot pressing and cold pressing treatments in sequence.

[0071] Further, after heating to 40 °C to 60 °C, it is necessary to stir for 5 h to 18 h to make it evenly mixed.

[0072] Furthermore, the drying temperature is 10 °C to 120 °C, and the drying time is 0.5 h to 15 h. Specifically, the drying temperature can be, but is not limited to, 10 °C, 20 °C, 30 °C, 40 °C, 50 °C, 60 °C, 70 °C, 80 °C, 90 °C, 100 °C, 110 °C, or 120 °C. The drying time can be, but is not limited to, 0.5 h, 1 h, 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h, 10 h, 11 h, 12 h, 13 h, 14 h, or 15 h.

[0073] It can be understood that the composite electrolyte material also includes a solvent, and the ratio of the solvent to the polymer electrolyte is (100 - 200) mL : (8 - 12) g. Further, the solvent includes an organic solvent. Specifically, the organic solvent can be, but is not limited to, N-methylpyrrolidone.

[0074] In a specific example, the single-sided thickness of the mixed material coated on the porous polyimide fiber membrane is 200 μm to 600 μm. Specifically, the single-sided thickness of the mixed material coated on the porous polyimide fiber membrane can be, but is not limited to, 200 μm, 250 μm, 300 μm, 350 μm, 400 μm, 450 μm, 500 μm, 550 μm, or 600 μm.

[0075] This application provides an electrolyte membrane, which is prepared by the preparation method described above. It can be understood that the electrolyte membrane includes a laminated porous polyimide fiber membrane and a composite electrolyte layer, and the composite electrolyte layer is provided on one or both sides of the porous polyimide fiber membrane.

[0076] Furthermore, the thickness of the electrolyte membrane is 15 μm to 25 μm. It can be understood that the thickness of the electrolyte membrane can be, but is not limited to, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, 21 μm, 22 μm, 23 μm, 24 μm or 25 μm.

[0077] In a specific example, the total thickness of the composite electrolyte layer is 5 μm to 10 μm. It can be understood that the total thickness here refers to the total thickness on both sides of the composite electrolyte layer after the final pressing step. The total thickness of the composite electrolyte layer can be, but is not limited to, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm or 10 μm.

[0078] This application also provides a lithium-ion battery, which includes a positive electrode, a negative electrode, and an electrolyte disposed between the negative electrode and the positive electrode. The electrolyte includes the electrolyte membrane as described above.

[0079] The following further describes this application in detail with specific embodiments. It should be understood that these embodiments are only used to illustrate this application and not to limit the scope of this application. For the experimental methods without specific conditions in the following embodiments, first refer to the guidance given in this application, and it can also be carried out according to the experimental manuals or conventional conditions in the art, or according to the conditions recommended by the manufacturer, or refer to the experimental methods known in the art.

[0080] In the following specific embodiments, for the measurement parameters of the raw material components, if there is no special description, there may be slight deviations within the weighing accuracy range. For the temperature and time parameters, acceptable deviations caused by instrument test accuracy or operation accuracy are allowed. "Normal temperature" refers to 25 °C; "atmospheric pressure" refers to 100 KPa or 101 KPa.

[0081] Example 1

[0082] This example provides an electrolyte membrane, and its preparation method includes the following steps:

[0083] Step 1: Cut a porous polyimide fiber membrane with a thickness of 10 μm (purchased from Jiangxi Xiancai Nanofiber Technology Co., Ltd., polyimide new energy battery separator) into a rectangular membrane with a size of 15×10 cm, rinse it with anhydrous ethanol, and dry it in an oven.

[0084] Step 2: Weigh 0.24 g of lithium aluminum titanium phosphate Li 1.5 Al0.5 Ti 1.5 (PO4)3 powder (purchased from Shenzhen Kejing Zhida Technology Co., Ltd., LATP - 300NM), 0.36 g of lithium bis(trifluoromethanesulfonyl)imide LiTFSI (Mackin, 99.9%), and 0.6 g of poly(vinylidene fluoride - hexafluoropropylene) PVDF - HFP (Mackin, Mw~800000) were placed in a container. Subsequently, 9 mL of N - methylpyrrolidone solvent (Mackin, 99.0%) was added for mixing, and magnetic stirring was carried out at room temperature for 3 h to ensure preliminary uniform mixing;

[0085] Step 3: Transfer the above - mentioned container to an oil bath at 50 °C and continue stirring for 12 h to obtain a milky white, uniform and viscous composite electrolyte slurry;

[0086] Step 4: Lay the dried porous polyimide fiber membrane flat on a glass plate, and use a 500 - μm - thick scraper to uniformly scrape the composite electrolyte slurry obtained in Step 3 onto one side surface of the fiber membrane at a speed of 40 mm / s;

[0087] Step 5: Move the glass plate to a vacuum oven, take it out after drying in vacuum at 80 °C for 1 h, turn the dried fiber membrane over and lay it flat on the glass plate, and use a 500 - μm - thick scraper to uniformly scrape the composite electrolyte slurry obtained in Step 3 onto the other side surface of the fiber membrane at a speed of 40 mm / s.

[0088] Step 6: Place the glass plate in a vacuum drying oven and dry it at 80 °C for 12 h to remove the solvent, obtaining a to - be - processed electrolyte membrane with a laminated porous polyimide fiber membrane and a composite electrolyte layer.

[0089] Step 7: Lay the to - be - processed electrolyte membrane obtained in Step 6 flat on a polytetrafluoroethylene film (purchased from Membrane Solutions, FPB005A12), then lay another polytetrafluoroethylene film on the other side surface of the electrolyte membrane, and then place the whole between two stainless - steel plates and put it into a hot press.

[0090] Step 8: Preheat at 120 °C for 10 min, then hot - press at a pressure of 5 MPa for 10 min. Subsequently, lower the temperature of the hot press plate to 25 °C and cold - press at a pressure of 5 MPa for 10 min, and peel off the polytetrafluoroethylene film to obtain the electrolyte membrane.

[0091] The parallel experimental data of the electrolyte membrane obtained in the above Example 1 are as shown in Nos. 1 - 5 in Table 1 below.

[0092] Table 1

[0093]

[0094] Example 2

[0095] This example provides an electrolyte membrane, and its preparation method includes the following steps:

[0096] Step 1: Cut a porous polyimide fiber membrane with a thickness of 10 μm (purchased from Jiangxi Xiancai Nanofiber Technology Co., Ltd., polyimide separator for new energy batteries) into a rectangular membrane sheet of 15×10 cm, rinse it with absolute ethanol, and dry it in an oven;

[0097] Step 2: Weigh 0.24 g of lithium lanthanum zirconium tantalum oxide Li 6.75 La3Zr 1.75 Ta 0.25 O 12 powder (purchased from Shenzhen Kejing Zhida Technology Co., Ltd., LLZTO-500nm), 0.36 g of lithium bis(trifluoromethanesulfonyl)imide LiTFSI (Mackin, 99.9%), and 0.6 g of poly(vinylidene fluoride - hexafluoropropylene) PVDF-HFP (Mackin, Mw~800000) into a container, then add 9 mL of N-methylpyrrolidone solvent (Mackin, 99.0%) for mixing, and stir magnetically at room temperature for 3 h to ensure preliminary uniform mixing;

[0098] Step 3: Transfer the above container to an oil bath at 50 °C, continue stirring for 12 h to obtain a milky white, uniform and viscous composite electrolyte material slurry;

[0099] Step 4: Lay the dried porous polyimide fiber membrane flat on a glass plate, and use a 500-μm-thick scraper to evenly scrape the composite electrolyte material slurry obtained in Step 3 onto one side surface of the fiber membrane at a speed of 40 mm / s;

[0100] Step 5: Move the glass plate to a vacuum oven, take it out after drying in vacuum at 80 °C for 1 h, turn the dried fiber membrane over and lay it flat on the glass plate, and use a 500-μm-thick scraper to evenly scrape the composite electrolyte material slurry obtained in Step 3 onto the other side surface of the fiber membrane at a speed of 40 mm / s.

[0101] Step 6: Put the glass plate into a vacuum drying oven, dry it at 80 °C for 12 h to remove the solvent, and obtain the electrolyte membrane to be processed.

[0102] Step 7: Lay the electrolyte membrane to be processed obtained in Step 6 flat on a polytetrafluoroethylene film (purchased from Membrane Solutions, FPB005A12), then lay another polytetrafluoroethylene film on the other side surface of the electrolyte membrane, and then place the whole between two stainless steel plates and put it into a hot press.

[0103] Step 8: Preheat at 120 °C for 10 min, then hot press at a pressure of 5 MPa for 10 min. Subsequently, lower the temperature of the hot press plate to 25 °C and then cold press at a pressure of 5 MPa for 10 min. Peel off the polytetrafluoroethylene film to obtain a laminated porous polyimide fiber membrane and an electrolyte membrane with composite electrolyte layers on both sides of the porous polyimide fiber membrane.

[0104] The parallel experimental data of the electrolyte membrane obtained in the above Example 2 are shown as No. 1 - 5 in Table 2 below.

[0105] Table 2

[0106]

[0107] Example 3

[0108] This example provides an electrolyte membrane, and its preparation method includes the following steps:

[0109] Step 1: Cut a porous polyimide fiber membrane with a thickness of 10 μm (purchased from Jiangxi Xiancai Nanofiber Technology Co., Ltd., polyimide separator for new energy batteries) into rectangular membrane pieces of 15×10 cm, rinse with absolute ethanol and then dry in an oven.

[0110] Step 2: Weigh 0.24 g of lithium germanium aluminum phosphate Li 1.5 Al 0.5 Ge 1.5 (PO4)3 powder (purchased from Shenzhen Kejing Zhida Technology Co., Ltd., LAGP), 0.36 g of lithium bis(trifluoromethanesulfonyl)imide LiTFSI (Mackin, 99.9%) and 0.6 g of poly(vinylidene fluoride - hexafluoropropylene) PVDF - HFP (Mackin, Mw~800000) into a container, then add 9 mL of N - methylpyrrolidone solvent (Mackin, 99.0%) for mixing, and magnetically stir at room temperature for 3 h to ensure preliminary uniform mixing.

[0111] Step 3: Transfer the above container to an oil bath at 50 °C and continue stirring for 12 h to obtain a milky white, uniform and viscous composite electrolyte material slurry.

[0112] Step 4: Lay the dried porous polyimide fiber membrane flat on a glass plate, and use a 500 - μm - thick scraper to uniformly scrape the composite electrolyte material slurry obtained in Step 3 onto the surface of the fiber membrane at a speed of 40 mm / s.

[0113] Step 5: Move the glass plate to a vacuum oven, take it out after drying in vacuum at 80 °C for 1 h. Turn over the dried fiber membrane and lay it flat on the glass plate. Use a 500-μm-thick scraper to evenly scrape the composite electrolyte material slurry obtained in Step 3 onto the surface of the fiber membrane at a speed of 40 mm / s.

[0114] Step 6: Place the glass plate in a vacuum drying oven and dry it at 80 °C for 12 h to remove the solvent, obtaining the electrolyte membrane to be processed.

[0115] Step 7: Lay the electrolyte membrane to be processed obtained in Step 6 flat on a polytetrafluoroethylene film (purchased from Membrane Solutions, FPB005A12), then lay another polytetrafluoroethylene film on the other surface of the electrolyte membrane, and then place the whole between two stainless steel plates and put it into a hot press.

[0116] Step 8: Preheat at 120 °C for 10 min, then hot press at a pressure of 5 MPa for 10 min. Subsequently, lower the temperature of the hot press plate to 25 °C and cold press at a pressure of 5 MPa for 10 min. Peel off the polytetrafluoroethylene film to obtain a laminated porous polyimide fiber membrane and an electrolyte membrane with composite electrolyte layers on both sides of the porous polyimide fiber membrane.

[0117] The parallel experimental data of the electrolyte membrane obtained in the above Example 3 are shown as No. 1-5 in Table 3 below.

[0118] Table 3

[0119]

[0120] Example 4

[0121] This example provides an electrolyte membrane, and its preparation method includes the following steps:

[0122] Step 1: Cut a porous polyimide fiber membrane with a thickness of 10 μm (purchased from Jiangxi Xiancai Nanofiber Technology Co., Ltd., polyimide separator for new energy batteries) into a rectangular film with a size of 15×10 cm, rinse it with absolute ethanol and dry it in an oven.

[0123] Step 2: Weigh 0.24 g of lithium aluminum titanium phosphate Li 1.5 Al 0.5 Ti 1.5(PO4)3 powder, 0.36 g lithium difluoroborate oxalate LiODFB (Mackin, 99.9%) and 0.6 g polyvinylidene fluoride - hexafluoropropylene PVDF - HFP (Mackin, Mw~800000) were placed in a container. Subsequently, 9 mL of N - methylpyrrolidone solvent (Mackin, 99.0%) was added for mixing, and magnetic stirring was carried out at room temperature for 3 h to ensure preliminary uniform mixing;

[0124] Step 3: Transfer the above container to an oil bath at 50 °C and continue stirring for 12 h to obtain a milky white, uniformly viscous composite electrolyte material slurry;

[0125] Step 4: Lay the dried porous polyimide fiber membrane flat on a glass plate, and use a 500 - μm - thick scraper to uniformly scrape the composite electrolyte material slurry obtained in Step 3 onto the surface of the fiber membrane at a speed of 40 mm / s;

[0126] Step 5: Move the glass plate to a vacuum oven, take it out after vacuum drying at 80 °C for 1 h. Turn the dried fiber membrane over and lay it flat on the glass plate, and use a 500 - μm - thick scraper to uniformly scrape the composite electrolyte material slurry obtained in Step 3 onto the surface of the fiber membrane at a speed of 40 mm / s.

[0127] Step 6: Place the glass plate in a vacuum drying oven and dry it at 80 °C for 12 h to remove the solvent, obtaining the electrolyte membrane to be processed.

[0128] Step 7: Lay the electrolyte membrane to be processed obtained in Step 6 flat on a polytetrafluoroethylene film (purchased from Membrane Solutions, FPB005A12), then lay another polytetrafluoroethylene film on the other surface of the electrolyte membrane, and then place the whole between two stainless - steel plates and put it into a hot press.

[0129] Step 8: Preheat at 120 °C for 10 min, then hot - press at a pressure of 5 MPa for 10 min. Subsequently, lower the temperature of the hot press plate to 25 °C and cold - press at a pressure of 5 MP for 10 min. Peel off the polytetrafluoroethylene film to obtain a laminated electrolyte membrane with a porous polyimide fiber membrane and composite electrolyte layers on both sides of the porous polyimide fiber membrane.

[0130] The parallel experimental data of the electrolyte membrane obtained in Example 4 above are shown as numbers 1 - 5 in Table 4 below.

[0131] Table 4

[0132]

[0133] Example 5

[0134] This embodiment provides an electrolyte membrane, and its preparation method includes the following steps:

[0135] Step 1: Cut a porous polyimide fiber membrane with a thickness of 10 μm (purchased from Jiangxi Xiancai Nanofiber Technology Co., Ltd., polyimide separator for new energy batteries) into a rectangular membrane sheet of 15×10 cm, rinse it with absolute ethanol, and dry it in an oven;

[0136] Step 2: Weigh 0.24 g of lithium aluminum titanium phosphate Li 1.5 Al 0.5 Ti 1.5 (PO4)3 powder, 0.36 g of lithium bis(trifluoromethanesulfonyl)imide LiTFSI (Mackin, 99.9%) and 0.6 g of polyethylene oxide PEO (Mackin, Mw~1000000) into a container, then add 10 mL of tetrahydrofuran solvent (Mackin, 99.0%) for mixing, and stir magnetically at room temperature for 3 h to ensure preliminary uniform mixing;

[0137] Step 3: Transfer the above container to an oil bath at 50 °C and continue stirring for 12 h to obtain a milky white, uniform and viscous composite electrolyte slurry;

[0138] Step 4: Lay the dried porous polyimide fiber membrane flat on a glass plate, and use a 300-μm-thick scraper to evenly scrape the composite electrolyte slurry obtained in Step 3 onto the surface of the fiber membrane at a speed of 40 mm / s;

[0139] Step 5: Place the glass plate at room temperature for 2 h to volatilize the solvent, then turn the fiber membrane over and lay it flat on the glass plate, and use a 300-μm-thick scraper to evenly scrape the composite electrolyte slurry obtained in Step 3 onto the surface of the fiber membrane at a speed of 40 mm / s.

[0140] Step 6: Place the glass plate at room temperature for 2 h to volatilize the solvent, and then put it into a vacuum oven at 60 °C to dry for 10 h to remove the solvent and obtain a to-be-treated electrolyte membrane.

[0141] Step 7: Lay the to-be-treated electrolyte membrane obtained in Step 6 flat on a polytetrafluoroethylene film (purchased from Membrane Solutions, FPB005A12), then lay another polytetrafluoroethylene film on the other surface of the electrolyte membrane, and then place the whole between two stainless steel plates and put it into a hot press.

[0142] Step 8: Preheat at 90 °C for 10 min, then hot press at a pressure of 5 MPa for 10 min. Subsequently, after reducing the temperature of the hot press plate to 25 °C, cold press at a pressure of 5 MPa for 10 min. Peel off the polytetrafluoroethylene film to obtain a laminated porous polyimide fiber membrane and an electrolyte membrane with composite electrolyte layers on both sides of the porous polyimide fiber membrane.

[0143] The parallel experimental data of the electrolyte membrane obtained in Example 5 above are shown as Nos. 1 - 5 in Table 5 below.

[0144] Table 5

[0145]

[0146] Comparative Example 1

[0147] This comparative example provides a method for preparing an electrolyte membrane, including the following steps:

[0148] Step 1: Weigh 0.24 g of lithium aluminum titanium phosphate Li 1.5 Al 0.5 Ti 1.5 (PO4)3 powder (purchased from Shenzhen Kejing Zhida Technology Co., Ltd., LATP - 300NM), 0.36 g of lithium bis(trifluoromethanesulfonyl)imide LiTFSI (Mackin, 99.9%) and 0.6 g of polyvinylidene fluoride - hexafluoropropylene PVDF - HFP (Mackin, Mw~800000) into a container. Subsequently, add 9 mL of N - methylpyrrolidone solvent (Mackin, 99.0%) and mix. Stir magnetically at room temperature for 3 h to ensure preliminary uniform mixing;

[0149] Step 2: Transfer the above container to an oil bath at 50 °C and continue stirring for 12 h to obtain a milky white, uniformly viscous composite electrolyte material slurry;

[0150] Step 3: Use a 500μm scraper to coat the composite electrolyte material slurry obtained in Step 2 on the surface of a glass plate. After scraping, place the glass plate in a vacuum drying oven and dry at 80 °C for 12 h to remove the solvent, thus obtaining the electrolyte membrane.

[0151] The parallel experimental data of the electrolyte membrane obtained in Comparative Example 1 above are shown as Nos. 1 - 5 in Table 6 below.

[0152] Table 6

[0153]

[0154] Comparative Example 2

[0155] This comparative example provides a method for preparing an electrolyte membrane, including the following steps:

[0156] Step 1: Cut a porous polyimide fiber membrane with a thickness of 10 μm (purchased from Jiangxi Xiancai Nanofiber Technology Co., Ltd., polyimide separator for new energy batteries) into a rectangular membrane with a size of 15×10 cm. After rinsing with absolute ethanol, dry it in an oven.

[0157] Step 2: Weigh 0.24 g of lithium aluminum titanium phosphate Li 1.5 Al 0.5 Ti 1.5 (PO4)3 powder (purchased from Shenzhen Kejing Zhida Technology Co., Ltd., LATP - 300NM), 0.36 g of lithium bis(trifluoromethanesulfonyl)imide LiTFSI (Mackin, 99.9%) and 0.6 g of polyethylene oxide PEO (Mackin, Mw~1000000) into a container. Then add 10 mL of tetrahydrofuran solvent (Mackin, 99.0%) and mix them. Stir magnetically at room temperature for 3 h to ensure uniform preliminary mixing.

[0158] Step 3: Transfer the above container to an oil bath at 50 °C and continue stirring for 12 h to obtain a milky white, uniform and viscous composite electrolyte material slurry.

[0159] Step 4: Lay the dried porous polyimide fiber membrane flat on a glass plate. Use a 300 - μm - thick scraper to uniformly scrape the composite electrolyte material slurry obtained in Step 3 onto the surface of the fiber membrane at a speed of 40 mm / s.

[0160] Step 5: Place the glass plate at room temperature for 2 h to volatilize the solvent. Then turn the fiber membrane over and lay it flat on the glass plate. Use a 300 - μm - thick scraper to uniformly scrape the composite electrolyte material slurry obtained in Step 3 onto the surface of the fiber membrane at a speed of 40 mm / s.

[0161] Step 6: Place the glass plate at room temperature for 2 h to volatilize the solvent, and then put it into a vacuum oven at 60 °C to dry for 10 h to remove the solvent, thus obtaining the electrolyte membrane.

[0162] The parallel experimental data of the electrolyte membrane obtained in the above Comparative Example 2 are shown as numbers 1 - 4 in Table 7 below.

[0163] Table 7

[0164]

[0165] Comparative Example 3

[0166] This comparative example provides a method for preparing an electrolyte membrane, including the following steps:

[0167] Step 1: Cut a porous polyimide fiber membrane with a thickness of 10 μm (purchased from Jiangxi Xiancai Nanofiber Technology Co., Ltd., polyimide separator for new energy batteries) into rectangular membrane sheets of 15×10 cm, rinse with absolute ethanol, and dry in an oven;

[0168] Step 2: Weigh 0.24 g of SiO2 (Mackin, 99.0%), 0.36 g of lithium bis(trifluoromethanesulfonyl)imide LiTFSI (Mackin, 99.9%), and 0.6 g of polyethylene oxide PEO (Mackin, Mw~1000000) into a container, then add 10 mL of tetrahydrofuran solvent (Mackin, 99.0%) for mixing, and stir magnetically at room temperature for 3 h to ensure preliminary uniform mixing;

[0169] Step 3: Transfer the above container to an oil bath at 50 °C and continue stirring for 12 h to obtain a milky white, uniform and viscous composite electrolyte material slurry;

[0170] Step 4: Lay the dried porous polyimide fiber membrane flat on a glass plate, and use a 300-μm-thick scraper to evenly scrape the composite electrolyte material slurry obtained in Step 3 onto the surface of the fiber membrane at a speed of 40 mm / s;

[0171] Step 5: Place the glass plate at room temperature for 2 h to volatilize the solvent, then turn the fiber membrane over and lay it flat on the glass plate, and use a 300-μm-thick scraper to evenly scrape the composite electrolyte material slurry obtained in Step 3 onto the surface of the fiber membrane at a speed of 40 mm / s.

[0172] Step 6: Place the glass plate at room temperature for 2 h to volatilize the solvent, and then put it into a vacuum oven at 60 °C to dry for 10 h to remove the solvent and obtain the electrolyte membrane to be processed.

[0173] Step 7: Lay the electrolyte membrane to be processed obtained in Step 6 flat on a polytetrafluoroethylene film (purchased from Membrane Solutions, FPB005A12), then lay another polytetrafluoroethylene film on the other surface of the electrolyte membrane, and then place the whole between two stainless steel plates and put it into a hot press.

[0174] Step 8: Preheat at 120 °C for 10 min, then hot press at a pressure of 5 MPa for 10 min, then lower the temperature of the hot press plate to 25 °C, and cold press at a pressure of 5 MPa for 10 min. Peel off the polytetrafluoroethylene film to obtain an electrolyte membrane with a laminated porous polyimide fiber membrane and composite electrolyte layers on both sides of the porous polyimide fiber membrane.

[0175] The parallel experimental data of the electrolyte membrane obtained in the above Comparative Example 3 are shown as No. 1-4 in Table 8 below.

[0176] Table 8

[0177]

[0178] Comparative Example 4

[0179] This comparative example provides a method for preparing an electrolyte membrane, which includes the following steps:

[0180] Step 1: Cut a porous polyimide fiber membrane with a thickness of 10 μm (purchased from Jiangxi Xiancai Nanofiber Technology Co., Ltd., polyimide separator for new energy batteries) into a rectangular membrane with a size of 15×10 cm. After rinsing with absolute ethanol, dry it in an oven;

[0181] Step 2: Weigh 0.24 g of lithium aluminum titanium phosphate Li 1.5 Al 0.5 Ti 1.5 (PO4)3 powder (purchased from Shenzhen Kejing Zhida Technology Co., Ltd., LATP - 300NM), 0.36 g of lithium bis(trifluoromethanesulfonyl)imide LiTFSI (Mackin, 99.9%) and 0.6 g of polyethylene oxide PEO (Mackin, Mw~1000000) into a container. Then add 10 mL of tetrahydrofuran solvent (Mackin, 99.0%) for mixing, and stir magnetically at room temperature for 3 h to ensure uniform preliminary mixing;

[0182] Step 3: Transfer the above container to an oil bath at 50 °C and continue stirring for 12 h to obtain a milky white, uniform and viscous composite electrolyte material slurry;

[0183] Step 4: Lay the dried porous polyimide fiber membrane flat on a glass plate, and use a 300 - μm - thick scraper to evenly scrape the composite electrolyte material slurry obtained in Step 3 onto the surface of the fiber membrane at a speed of 40 mm / s;

[0184] Step 5: Place the glass plate at room temperature for 2 h to volatilize the solvent, then turn the fiber membrane over and lay it flat on the glass plate, and use a 300 - μm - thick scraper to evenly scrape the composite electrolyte material slurry obtained in Step 3 onto the surface of the fiber membrane at a speed of 40 mm / s.

[0185] Step 6: Place the glass plate at room temperature for 2 h to volatilize the solvent, and then put it into a vacuum oven at 60 °C to dry for 10 h to remove the solvent, obtaining the electrolyte membrane to be processed.

[0186] Step 7: Lay the electrolyte membrane to be processed obtained in Step 6 flat on a polytetrafluoroethylene film (purchased from Membrane Solutions, FPB005A12), then lay another polytetrafluoroethylene film on the other surface of the electrolyte membrane, and then place the whole between two stainless steel plates and put it into a hot press.

[0187] Step 8: Preheat at 120 °C for 10 min, then hot press at a pressure of 5 MPa for 10 min, and peel off the polytetrafluoroethylene film to obtain the electrolyte membrane.

[0188] The parallel experimental data of the electrolyte membrane obtained in the above Comparative Example 4 are shown as Nos. 1 - 5 in Table 9 below.

[0189] Table 9

[0190]

[0191] Comparative Example 5

[0192] This comparative example provides a method for preparing an electrolyte membrane, including the following steps:

[0193] Step 1: Cut a porous polyimide fiber membrane with a thickness of 10 μm (purchased from Jiangxi Xiancai Nanofiber Technology Co., Ltd., polyimide separator for new energy batteries) into a rectangular membrane with a size of 15×10 cm, rinse it with absolute ethanol, and dry it in an oven.

[0194] Step 2: Weigh 0.24 g of lithium aluminum titanium phosphate Li 1.5 Al 0.5 Ti 1.5 (PO4)3 powder (purchased from Shenzhen Kejing Zhida Technology Co., Ltd., LATP - 300NM), 0.36 g of lithium bis(trifluoromethanesulfonyl)imide LiTFSI (Mackin, 99.9%) and 0.6 g of polyethylene oxide PEO (Mackin, Mw~1000000) into a container, then add 10 mL of tetrahydrofuran solvent (Mackin, 99.0%) for mixing, and magnetically stir at room temperature for 3 h to ensure preliminary uniform mixing.

[0195] Step 3: Transfer the above container to an oil bath at 50 °C and continue stirring for 12 h to obtain a milky white, uniform and viscous composite electrolyte material slurry.

[0196] Step 4: Lay the dried porous polyimide fiber membrane flat on a glass plate, and use a 300 - μm - thick scraper to uniformly scrape the composite electrolyte material slurry obtained in Step 3 onto the surface of the fiber membrane at a speed of 40 mm / s.

[0197] Step 5: Place the glass plate at room temperature for 2 h to volatilize the solvent. Then turn the fiber membrane over and lay it flat on the glass plate. Use a 300-μm-thick scraper to evenly scrape the composite electrolyte material slurry obtained in Step 3 onto the surface of the fiber membrane at a speed of 40 mm / s.

[0198] Step 6: Place the glass plate at room temperature for 2 h to volatilize the solvent, and then put it into a vacuum oven at 60 °C and dry for 10 h to remove the solvent, obtaining the electrolyte membrane to be treated.

[0199] Step 7: Lay the electrolyte membrane to be treated obtained in Step 6 flat on a polytetrafluoroethylene film (purchased from Membrane Solutions, FPB005A12). Then lay another polytetrafluoroethylene film on the other surface of the electrolyte membrane. Then place the whole between two stainless steel plates and put it into a hot press.

[0200] Step 8: Cold press at a pressure of 5 MPa for 10 min, and peel off the polytetrafluoroethylene film to obtain the laminated porous polyimide fiber membrane and the electrolyte membrane with composite electrolyte layers on both sides of the porous polyimide fiber membrane.

[0201] The parallel experimental data of the electrolyte membrane obtained in the above Comparative Example 5 are shown as No. 1-5 in Table 10 below.

[0202] Table 10

[0203]

[0204] Comparative Example 6

[0205] This comparative example provides a method for preparing an electrolyte membrane, including the following steps:

[0206] Step 1: Cut a 10-μm-thick porous polyimide membrane (purchased from Shenzhen Raytron Thin Film Technology Co., Ltd., electronic series polyimide film) into a rectangular film piece of 15×10 cm, rinse it with absolute ethanol, and dry it in an oven.

[0207] Step 2: Weigh 0.24 g of lithium lanthanum zirconium tantalum oxide Li 6.75 La3Zr 1.75 Ta 0.25 O 12The powder (purchased from Shenzhen Kejing Zhida Technology Co., Ltd., LLZTO - 500nm), 0.36 g of lithium bis(trifluoromethanesulfonyl)imide LiTFSI (Mackin, 99.9%), and 0.6 g of poly(vinylidene fluoride - hexafluoropropylene) PVDF - HFP (Mackin, Mw~800000) were placed in a container. Subsequently, 9 mL of N - methylpyrrolidone solvent (Mackin, 99.0%) was added for mixing, and magnetic stirring was carried out at room temperature for 3 h to ensure preliminary uniform mixing;

[0208] Step 3: Transfer the above - mentioned container to an oil bath at 50 °C and continue stirring for 12 h to obtain a milky white, uniformly viscous composite electrolyte material slurry;

[0209] Step 4: Lay the dried porous polyimide fiber membrane flat on a glass plate, and use a 500 - μm - thick scraper to uniformly scrape the composite electrolyte material slurry obtained in Step 3 onto one side surface of the fiber membrane at a speed of 40 mm / s;

[0210] Step 5: Move the glass plate to a vacuum oven, take it out after drying in vacuum at 80 °C for 1 h, turn the dried fiber membrane over and lay it flat on the glass plate, and use a 500 - μm - thick scraper to uniformly scrape the composite electrolyte material slurry obtained in Step 3 onto the other side surface of the fiber membrane at a speed of 40 mm / s.

[0211] Step 6: Place the glass plate in a vacuum drying oven and dry it at 80 °C for 12 h to remove the solvent, obtaining the electrolyte membrane to be processed.

[0212] Step 7: Lay the electrolyte membrane to be processed obtained in Step 6 flat on a polytetrafluoroethylene film (purchased from Membrane Solutions, FPB005A12), then lay another polytetrafluoroethylene film on the other side surface of the electrolyte membrane, and then place the whole between two stainless - steel plates and put it into a hot press.

[0213] Step 8: Preheat at 120 °C for 10 min, then hot - press at a pressure of 5 MPa for 10 min. Subsequently, lower the temperature of the hot press plate to 25 °C and cold - press at a pressure of 5 MPa for 10 min, and peel off the polytetrafluoroethylene film to obtain the electrolyte membrane.

[0214] The parallel experimental data of the electrolyte membrane obtained in the above Comparative Example 6 are shown as No. 1 - 5 in Table 11 below.

[0215] Table 11

[0216]

[0217] The electrochemical performances of the electrolyte membranes of the above embodiments and comparative examples after being used in the LiFePO4 / / Li solid-state battery are summarized in Table 12 below.

[0218] Table 12

[0219]

[0220] As Figure 1 shown is the scanning electron microscope image of the porous polyimide fiber membrane used in Example 1; as Figure 2 shown is the scanning electron microscope image of the electrolyte membrane prepared in Example 1; as Figure 3 shown is the electrochemical impedance spectrum of the electrolyte membrane prepared in Example 1; as Figure 4 shown is the tensile resistance of the electrolyte membranes prepared in Example 1 and Comparative Example 1; as Figure 5 is the linear sweep voltammogram of the electrolyte membrane prepared in Example 1; Figure 6 are the charge and discharge cycle data of the LiFePO4 / / Li solid-state battery with the electrolyte membranes prepared in Example 1 and Comparative Example 1 at a rate of 0.5C.

[0221] The electrolyte membrane provided by this application has a small thickness (which can reduce the internal resistance of the whole battery), a high ionic conductivity (> 10 -4 Scm -1 ), a strong ability to resist the formation of lithium dendrites, and a high electrochemical stability (electrochemical stability window > 4.7 V). The lithium-ion battery assembled with this membrane has important advantages such as a high charge and discharge capacity and good battery cycle stability. In addition, the introduction of the porous polyimide fiber membrane greatly enhances the mechanical properties and thermal stability of the electrolyte membrane, solving the problems of the current inorganic electrolyte membrane with a large thickness and low mechanical strength (easy to break), and the problems of the organic electrolyte membrane with poor thermal stability. At the same time, the combination of the hot pressing and cold pressing processes adopted can effectively control the overall thickness and uniformity of the membrane sheet, and the composite electrolyte on the surface can be pressed into the pores of the porous fiber membrane to form a continuous ion transport channel.

[0222] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which this application belongs. The terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0223] The technical features of the above embodiments can be combined arbitrarily. For the sake of concise description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered to be within the scope described in this specification.

[0224] The above-described embodiments merely represent several implementation manners of the present application, which are convenient for understanding the technical solution of the present application specifically and in detail, but should not be construed as limiting the scope of patent protection of the application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all fall within the protection scope of the present application. It should be understood that the technical solutions obtained by those skilled in the art through logical analysis, reasoning or limited experiments on the basis of the technical solutions provided by the present application are all within the protection scope of the appended claims of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the content of the appended claims, and the specification can be used to interpret the content of the claims.

Claims

1. A method for preparing an electrolyte membrane, characterized in that, It includes the following steps: After setting the composite electrolyte material on one or both sides of the porous polyimide fiber membrane, hot pressing treatment and cold pressing treatment are carried out in sequence to make the composite electrolyte material enter the porous polyimide fiber membrane and prepare a composite electrolyte layer; Among them, the composite electrolyte material includes a polymer electrolyte, a filler, and a lithium salt with a mass ratio of (8~12) : (1~6) : (1~8).

2. The preparation method according to claim 1, characterized in that, The hot pressing treatment satisfies one or more of the following conditions: (1) The temperature of the hot pressing treatment is 50°C to 140°C; (2) The pressure of the hot pressing treatment is 2 MPa to 10 Mpa; (3) The time of the hot pressing treatment is 4 min to 15 min.

3. The preparation method according to claim 1, characterized in that, The cold pressing treatment satisfies one or more of the following conditions: (1) The temperature of the cold pressing treatment is 20°C to 40°C; (2) The pressure of the cold pressing treatment is 2 MPa to 10 Mpa; (3) The time of the cold pressing treatment is 4 min to 15 min.

4. The preparation method according to claim 1, characterized in that, The porous polyimide fiber membrane satisfies one or more of the following conditions: (1) The thickness is 10μm to 15μm; (2) The porosity is 70% to 90%; (3) The equivalent pore size is 0.6μm to 11μm.

5. The preparation method according to claim 1, characterized in that, The preparation method of the composite electrolyte layer includes the following steps: Mix the composite electrolyte material according to the mass ratio, heat it to 40°C to 60°C, and prepare a mixture; Coat the mixture on one or both sides of the porous polyimide fiber membrane, and after drying, carry out hot pressing treatment and cold pressing treatment in sequence.

6. The preparation method according to claim 5, characterized in that, It satisfies one or more of the following conditions: (1) After heating to 40°C to 60°C, mix for 5h to 18h to prepare the mixture; (2) The drying time is 0.5h to 15h; (3) The drying temperature is 10°C to 120°C; (4) The composite electrolyte material further includes a solvent, and the ratio of the solvent to the polymer electrolyte is (100~200) mL : (8~12) g; (5) The single-sided thickness of the mixture coated on the porous polyimide fiber membrane is 200μm to 600μm.

7. The preparation method according to any one of claims 1 to 5, characterized in that, The composite electrolyte material satisfies one or more of the following conditions: (1) The polymer electrolyte includes one or more of polyacrylic acid, polyvinylidene fluoride, polyvinylidene fluoride - hexafluoropropylene, polyethylene oxide, and polyacrylonitrile; (2) The filler includes one or more of lithium lanthanum zirconium tantalum oxide solid electrolyte, lithium lanthanum zirconium oxide solid electrolyte, lithium titanium aluminum phosphate solid electrolyte, lithium germanium aluminum phosphate solid electrolyte, and lithium lanthanum titanate solid electrolyte; (3) The lithium salt includes one or more of CH2LiNOS, LiN(CN)2, Li(CF3SO2)3C, LiC4F9SO3, LiN(SO2CF2CF3)2, LiB(C2O4)2, LiBOB, LiBF4, LiBF3(C2F5), LiODFB, LiTFSI, LiFSI, LiAsF6, LiSbF6, and LiClO4.

8. An electrolyte membrane, characterized in that, It is prepared according to the preparation method described in any one of claims 1 to 7.

9. The electrolyte membrane according to claim 8, wherein, Meet one or both of the following conditions: (1) The thickness of the electrolyte membrane is 15 μm to 25 μm; (2) The total thickness of the composite electrolyte layer is 5 μm to 10 μm.

10. A lithium-ion battery, characterized in that, It includes a positive electrode, a negative electrode, and an electrolyte disposed between the negative electrode and the positive electrode, and the electrolyte includes the electrolyte membrane as described in claim 8 or 9.

Images